There isn't any reason why you couldn't crush them and put them right into the soil, but I would work them in with a shovel or something, or the critters might just eat them. They'll break down rapidly. I too believe that sugar, especially, will promote rapid bacterial/fungal growth of beneficial microbes.

You could also put them into your compost -- I don't think it matters, really, just a question of how soon they reach the ultimate resting spot, your soil.

When it comes to things like grains I am an advocate of composting in place. They decompose quickly.

I am not a fan of composting in place with plant matter during the growing season simply because I have seen this result in a large population of bugs that eat decomposing matter that then go on to nibble and the live plants. Of course working it into the soil or doing it out of season would be fine.

If you have ever looked up the nutrient content of compost it is very low. Much lower than the total of what was in the raw organic matter. I suspect this is due to rain leeching a lot of the good stuff out and probably other factors so to me composting in place makes a lot of sense.

The sugar on those flakes wil be attractive to a fairly large number of unwanted critters if you simply throw them onto your soil. Composting that stuff would be better.

The sugar on those flakes wil be attractive to a fairly large number of unwanted critters if you simply throw them onto your soil.

What if I dug it into the soil as justaguy says? What kind of critters might I have to wory about?

If you have ever looked up the nutrient content of compost it is very low. Much lower than the total of what was in the raw organic matter. I suspect this is due to rain leeching a lot of the good stuff out and probably other factors so to me composting in place makes a lot of sense.

I've always noticed that if I dig in my half finished compost into the soil, the worms go nuts over it. Hundreds of them find their way to it. If I dig in finished compost, there's not a large difference in the worms.

I assume the same goes for all the other decomposers too. Because of this, I prefer unfinished materials, or trench composting. I've just become aware of using grain and seed meals as a fertilizer, so I want to try it but all I have access to is corn gluten meal and I don't want to mess with seed germination.

"If you have ever looked up the nutrient content of compost it is very low."
That is because the nutrients in compost are very stable, not soluble, not easy extracted for the soil tests. The nutrients are there and will be made available to plants by soil bacteria, but because those nutrients are not easily extracted compost is labeled a soil amendment and not a fertilizer.